There is really no reason to use Effect Spore. You're betting on a move that may not even activate or get you a decent status effect in a format where Amoonguss can easily be OHKO'd by several restricted legends, not to mention plenty of special attackers in the format which don't make contact to activate ES.
If you land on Poison, it doesn't really net you much since most games in VGC'16 take fewer than 5 turns, and nearly every Pokemon in the format can be OHKO'd by another.
Paralysis is decent, but lots of teams are falling back on Trick Room nowadays, so you are potentially helping them out (minus the chance of full para).
As for Sleep, you already have Spore, which has perfect accuracy. No need to gamble on a gimmick ability. If you live a hit, you can switch out for some healing with Regenerator.
To be honest, if you want something that deters Mega Kangaskhan, you're best off with Ferrothorn (or another Khan, but that's beside the point). It can safely come in on anything it commonly uses aside Low Kick and will deal respectable Barbs damage to it in return. Not to mention Ferro is a great way to deal with Xerneas and P-Kyogre.